I don't know if this problem still exists in OSX 10.5 - hopefully not, but it might?
I automatically downloaded an MP3. It saved with the entire extension, including the garbage after the ? that the web server on the other end needed.
When I try to change the end of the name to .mp3 instead of the mess I had, I got this popup:
Oops! Arrow keys don't work, the only way out is to keep the existing file.
Once again, I'm stuck using the unholy COMMAND LINE on my Macintosh...
mv 200135320_S64.mp3\?e\=1233269155\&h\=be87cefbe9b07d9d1ede71855e095956 200135320_S64.mp3
Now, the file works.